12V AUX Battery replacement on 2007 Prius with Smart Entry?

You can do the job yourself and save some money. The battery is expensive and there are not a lot of choices on that. Exide makes one, O'Reilly Auto Parts stocks one, Toyota OEM battery, and the Yellow Top. Again it is a DIY job, pretty simple IF you are mechanically inclined. There is also a link in my signature which details how to change the battery. I did the work myself. I have also read that a lady was able to do it (Julia 2001) I believe.

Unless you have money to burn, don't let the dealers do the job for you. They are going to charge a lot extra for the install. Some say $50, others want $150 plus the battery.

The battery is a AGM type with "Reversed JIS Posts". It is also rather small and low AMP Hour. It is also a special vented type battery. It is NOT a traditional flooded acid battery that is found in most cars and trucks. Lot's of info here on PC and the web concerning the 12 volt. Again, don't be afraid. You can do the work if you are mechanically inclined.

One other thing. If the car does not have SKS, you will probably have to change the tray when you get the new battery. The tray is available from Toyota. If you need help, I can give you a website you can go to get the tray. Any Toyota dealer should have the tray. If you have SKS, then you don't need to worry about the tray as the new battery will fit fine.

Hope this helps you and Welcome to Prius Chat!

 

Is the Yellow Top any cheaper?

(I'm in the "stay with OEM" camp, for 12 Volt batterys. Mainly for fit issues.)

 

Check the voltage of ANY battery you get with a digital voltmeter. A fully charged AGM battery should read at least 13.1 volts or higher. Don't accept it if it is around 12.6 or lower as it is NOT fully charged. You really do not want to put the battery in if it is NOT fully charged. If you have a good "smart" charger that will charge AGM type batteries you should charge the battery fully IF it is not fully charged before you install it. By doing so, you are actually lengthening the life of your new battery.

The NEW OEM Battery I got measured 13.1 with my meter. Also, a Yellow Top representative has posted here on Prius Chat and he too states that a fully charged Yellow Top will measure 13.1 volts.

So with all that said, don't accept a weak battery. That is not a good way to start. Make sure you get a fresh one that is fully charged. I don't knock Yellow Tops but there has been posts here on Prius Chat about Yellow Tops being sold that were not fully charged. It is because they set on a shelf for a long time before they were sold. ALL batteries are subject to this problem, it is not just the Yellow Top.

Hope this helps you, and best of luck to you!

 

You will not regret. You mad the good choice. Yellow top is for high demand and last long. It fits exactly(with SKS) and they comes with everything and instruction. Clear and easy to install. A pleasure to do it. I installed one three yrs ago in an hour, easy and gentle and I took my time, not rush. and it works wonderfully. I also got it the same price three yrs ago. Free and fast hipping. I rec'd it in three days. Good packing.

 

I just ordered the optima yellow top battery myself. It's worth noting that there are two yellow top batteries that fit the Prius, the DS46B24R and the D51. The DS46B24R is a direct replacement for the larger battery while the D51 needs retrofit kit for the lugs. Those with the smaller non-keyless battery can use the DS46B24R as well by purchasing the correct battery tray bracket or just spacing out the existing bracket as many here have done.

If you look online you'll see a lot of bad reviews for Optima batteries in general. This is because people put the Optima AGM style battery into cars that were not designed for AGM batteries and they do not charge correctly. AGM batteries need 13.8v or more to get into saturation charge. The Prius however is designed for AGM batteries.

 

I don't have the SKS, but I see ApexBattery has the DS46B24R on sale for $149. I should be able to use the larger battery anyway, right? Then I don't have to worry about the tray size or retrofit lug kit as well.

Oops, never mind, just read the end of your paragraph...

 

Well, not as easy as I thought. The DS46B24R is just a bit too big for the battery tray, so I ended up taking out the battery tray and rebending the one arm (maybe that's what goldfinger meant above?). Doesn't look fancy, but it works. I put another inch on it before it bends up, as it turns out it only needed maybe 3/8" (1 cm), so after the battery was in place, I slid in a piece of wood between the battery and the rear wall of the car, so it doesn't slide around at all. Then tightened down the brace and the attachments, it should be pretty good now. While I was in the trunk, I put more air in the spare tire, it was down to 20 PSI.

As a side note, this is to replace the original OEM battery on my car, which I bought in Feb. 2006, so that's 7.5 years old now. I took some voltage readings using the MFD diagnosis menu. Mind you, this was in the morning after the car sat overnight at 40'F (about 4'C):
IG on, no accessories: 11.8 V (was 12.1 V last spring)
ACC on: 11.4 V (was 11.8 last spring)
ACC on, with headlights: 11.1 V (was 11.4)
Engine on, charging: 14.2 V (same)

So it was clearly getting to be time to change the battery. For reference, the Optima was at 12.6 V (measured with voltmeter, and also using MFD Diagnosis menu), after sitting in a 50'F garage for a couple days.

 

To make the DS46B24R fit in a non SKS Prius, the fix is to change the battery tray. That part is available at the dealer. The hold down bracket is identical in both models, but due to the fact that two different batteries are used in the Prius, they used two different trays.

12.6 volts is a little low on your new battery. A fully charged Optima will measure 13.1 volts at the posts before it is hooked up. Also a fully charged AGM battery in the Prius should read out the following on the MFD.

Accessory Mode: 12.6 volts or higher
Ignition Mode: 12.4 volts or higher
Ready Mode: 13.8 to 14.2 volts.

Best of luck to you.

 

Well, I guess that's the recommended method. With a vise and a hammer and a good pair of pliers I was able to improvise a bit... That added about 45 minutes, whole thing took maybe 1.5 hours. I took out the black box beside the battery, but not the air duct, I was able squeeze the batteries around it (with some wiggling).

Okay, looks like I got accessory and ignition modes backwards. I am reading 12.6 in Acc now, but Ignition is 12.2. The manufacture date on the battery is 9/13, so it's probably been sitting on a shelf for 2 months. That's not too long, but enough for some discharge to occur, hopefully a few half-hour commutes will bring it back up. I'll check it again in a couple days. Also, I'm not sure if the cool temperature affected the reading much.

Thanks for sharing your knowledge

 

Hopefully the charging system will bring it back up for you. If you have a smart charger there, try hooking it up to the jump post under the hood and let if charge the battery up fully for you. A good smart charger once a month will make that battery last a long time. You are lucky you don't have the SKS. With that system, folks have problems with that when the voltage starts dropping off like yours was. But SKS is a nice thing too. Have it our Prius, it is nice to not have to fiddle with the car fob. It stays in my pocket all of the time.

FWIW, your Ignition Mode sounds a little low. Maybe you had more stuff running that I normally do. When I run the test, I keep the headlights off and the climate control turned off as well as radio and other electrical loads. Normally there is about a .2 of a volt variation between the accessory mode and the ignition on mode.

Sounds like you got a handle on it. Best of luck to you!